Force rescanning of available slicing profiles for slicer on update

Should make newly uploaded profiles available in the slicing dialog without
having to first deselect and then reselected the current slicer.

src/octoprint/static/js/app/viewmodels/slicing.js

@@ -102,6 +102,7 @@ $(function() {
 
             if (selectedSlicer != undefined) {
                 self.slicer(selectedSlicer);
+                self.profilesForSlicer(selectedSlicer);
             }
 
             self.defaultSlicer = selectedSlicer;